Grab stabilizer for cranes



April 1966 M. DECHANTSREITER 3,247,974

GRAB STABILIZER FOR CRANES Filed May 11, 1964 2 Sheets-Sheet l &

A r-roeivEy April 1966 M. DECHANTSREITER 3,247,974

GRAB STABILIZER FOR CRANES 2 Sheets-Sheet 2 Filed May 11, 1964 W) INVENTOR Mfix DECHHNTfiPE/TEK Em A 7'7'0ENEY United States Patent 3,247,974 GRAB STAIHLIZER FOR CRANE Max Dec-hantsreiter, Milwaukee, Wis, assignor to Harnischfeger QOrpOration, Milwaukee, Wis., a corporation of Wisconsin Filed May 11, 1964. Ser. No. 366,241 3 Claims. (Cl. 212--11) The present invention relates generally to mobile gantry cranes of the anti-sway type. More particularly, the invention relates to an anti-sway, telescopic mast for such a gantry crane, which mast is rotatable about a vertical axis and has load levelling mechanism.

Anti-sway mechanisms have heretofore been used with some degree of success, but they have had certain shortcomings and disadvantages. For example, they required a complex system of cross weaved cables, such as shown in US. Patent No. 3,081,884, or required extra motors and braking means. These prior art devices were not sufficiently positive and accurate in preventing all sway, and furthermore did not permit flexibility of movement of the load, particularly in a rotational direction about a vertical axis, or in leveling of the load.

Accordingly, the present invention provides a mobile gantry crane which has a vertically telescoping mast that positively prevents sway in all directions and which insures accurate and positive control of the load at all times. This mast is mounted for rotation about its own vertical axis to permit the load to be rotated 180 degrees to facilitate picking up, moving, and stacking of the load. Another more limited aspect relates to a gantry crane having a mast of the above type and which has mechanism for leveling the load in at least one direction.

Generally, the invention provides an improved mobile gantry crane having a vertical, rigid and telescoping mast which mast is also rotatable about a vertical axis; a more specific aspect relates to a crane of this type in which the mast is carried by a turret on a transversely movable trolley, and which trolley also carries the load leveling means.

These and other objects and advantages of the present invention will appear later as this disclosure progresses, reference being had to the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a mobile gantry crane which embodies the present invention;

FIGURE 2 is a plan view of the crane shown in FIG- URE 1.

Referring in greater detail to the drawings, the crane has four vertical shear legs 1, 2, 3 and 4. These legs depend downwardly from the large, rigid and rectangle frame F that is comprised of two transverse main girders 5, 6 and two longitudinal cross beams 7 and 8. The legs,

girders and cross beams are all rigidly welded or otherwise secured together to form a single, rigid mobile frame having ground engaging wheel means 10 and 11 at the lower ends of the legs. These ground engaging wheels may be of different types or a combination of types. For example, all legs may be equipped with rubber tired wheel means 10 or with flanged wheel means 11 which travel on tracks 12. In the embodiment shown for illustrative purposes, a combination of different wheel means is used, two of the legs 3 and 4 having the flanged wheel means type while legs 1 and 2 are equipped with the rubber tired wheel means.

The drive for the gantry crane is conventional and comprises two separate drive trains, one for .each drive wheel. For example, two squirrel cage electric motors M (only one shown) drive through a speed reducer 13 and a chain drive 14 to the rubber wheels 10.

The crane also has a transversely movable trolley T which moves along tracks 16 and 17 that extend adjacent along and are secured to the girders S and 6, respectively. More particularly, the trolley has four flanged wheels 19 which ride on and are guided by the tracks 16 and 17.

The drive for the trolley takes the form of a hoist 20 at one side of the crane and having squirrel cage electric motors 21 with conventional electrical-mechanical brakes (not shown). This hoist, through gear means 22, drives a shaft 23 having rope drums 24 and 25 fixed at the ends thereof. Wire ropes 26 and 27 are wound on drums 24 and 25 respectively, are trained over idler pulleys 28 at the opposite side of the crane. The wire ropes 26 and 27 are fixed at their opposite ends to the trolley at 29, 30 and 31, 32, respectively.

The drums are thus rotated in either direction to cause the trolley to move in either transverse direction across the crane in the conventional manner.

A rotatable turret is mounted on the upper side of the trolley by six wheels 36 which ride on and are guided by a circular track 37 secured to the upper side of the trolley. Four side thrust rollers 37a (FIGURE 2) are mounted on vertical axes on the turret and bear against the inner vertical side 37b of the channel iron roller circle 370 which forms part of the trolley. This construction insures that the turret remains concentric on the trolley circle and sidewise shifting of the turret cannot occur. The turret is fabricated from two straight members 33, 39, and a large arcuate member 40, all of which are welded together. The wheels or rollers 36 are rotatably mounted on the arcuate member. Suitable cross-braces 42, 43, 44, and are also welded across the members to form a rigid, single turret.

The turret is rotated by the electric, motor drive, rope drum 47 which is carried by the trolley. A wire rope 48 extends around the drum 47, around suitable idler pulleys 4), and its free ends are secured to opposite sides of the turret. The drum can be rotated in either direction to rotate the turret selectively in either direction to any degree. Suitable and conventional limit switches prevent overtravel and rotational speed may be in the order of 1 rpm.

A vertical mast 50 is rigidly secured to and extends downwardly from the turret 35. This mast is of rectangular cross-sectional shape and is of telescoping construction. The mast includes a relatively short upper section 51 which is rigidly secured as by welding to the turret, and more specifically to braces 42, 43, 44, and 45 thereof. An intermediate section 52 is vertically slidable within section 51, and a third or lower section 53 in turn is vertically slidable within the intermediate section. Thus, a considerable range of vertical extension and contraction of the mast is possible. Due to the relatively large cross section of the mast and its rectangular form, no swaying or twisting of the mast or its load can occur.

A grapple means is provided at the lower end of the mast and this includes a grapple frame which is pivotally mounted by two separate axes 6i and 62 which are arranged at right angles to one another. Telescoping grapple arms 64 extend downwardly from the grapple frame 60 and their lower shoes 65 engage the bottom of the load L. The length of the arms can be adjusted by the pins 66 which extend through alignable holes in the parts 64a and 64b of the arms.

Means are provided for actuating the graple arms but as it, per se, forms no part of the present invention, it is believed suflicient to say that a hydraulic power pack is powered by an electric motor and supplies pressure fluid to grapple arm clamp and raise cylinders.

The load is thus capable of swinging within limits from side to side about pivot shaft 62, and in a longitudinal di- G rection about shaft 61. This facilitates the gentle lowering of the load on an uneven surface.

Means are also provided for leveling the load in a transverse direction, that is, about the pivot shaft 62. This means takes the form of a pair of elevating mechanisms 68 and 69, one mounted at either side of the top of the turret. These mechanisms are similar to one another and each include an electric motor 70 which drives a winch drum 72, suitable pulleys 74 mounted on the grapple frame and pulleys 75 on the turret. Wire ropes 73 and 73a are trained over the drums and pulleys. The mechanisrns 68 and 69 can be operated independently of one another to thereby effect load leveling.

RECAPITULATION The present invention provides a mobile gantry crane having a vertical, rigid and telescoping mast that positively prevents sway and permits accurate handling of the load. The mast can be rotated above a vertical axis which greatly facilitates picking up, moving and stacking the load, at either side of the crane, and provision is also made on the mast and turret for leveling the load.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention:

1. A mobile crane comprising, an elevated frame, a trolley movable along said frame, a turret rotatably mounted about a vertical axis on said trolley, a vertical mast rigidly fixed at its upper end to said turret and extending downwardly therefrom, said mast being of rectangular cross section and having a plurality of telescoping sections, grapple means at the lower end of said mast for engaging a load to be elevated by contraction of said mast, two pivot axes arranged at right angles to one another at the lower end of the mast for connecting the grapple means thereto, and a pair of load elevating mechanisms carried by said turret and connected to said grapple means, said mechanisms being located one on each side of said turret and operable independently of one another whereby a load carried by said grapple means can be levelled about one of said pivot axes.

2. A crane as defined in claim 1 including four downwardly extending legs for supporting said elevated frame above the ground and wheel means at the lower ends of said legs.

3. A crane as defined in claim 2 further characterized in that there are at least three telescoping sections, the uppermost section being shorter than the others and less than one-quarter the length of the said legs to thereby give a considerable range of vertical extension.

References Cited by the Examiner UNITED STATES PATENTS 979,173 12/1910 Kruger 212-67 2,306,055 12/ 1942 Harry 212127 2,553,378 5/1951 Miller 21221 2,869,734 1/1959 Erenestus 21221 3,051,321 8/1962 Ramsden 212-14 3,175,085 3/1965 Avery 212 X FOREIGN PATENTS 1,277,706 10/ 1961 France. 1,068,628 11/ 1959 Germany. 1,074,241 1/ 1960 Germany. 125,312 6/ 1949 Sweden.

SAMUEL F. COLEMAN, Primary Examiner.

A. IL. LEVINE, Assistant Examiner. 

1. A MOBILE CRANE COMPRISING, AN ELEVATED FRAME A TROLLEY MOVABLE ALONG SAID FRAME, A TURRET ROTATABLY MOUNTED ABOUT A VERTICAL AXIS ON SAID TROLLEY, A VERTICAL MAST RIGIDLY FIXED AT ITS UPPER END TO SAID TURRET AND EXTENDING DOWNWARDLY THEREFROM, SAID MAST BEING OF RECTANGULAR CROSS SECTION AND HAVING A PLURALITY OF TELESCOPING SECTIONS, GRAPPLE MEANS AT THE LOWER END OF SAID MAST FOR ENGAING A LOAD TO BE ELEVATED BY CONTRACTION OF SAID MAST, TWO PIVOT AXES ARRANGED AT RIGHT ANGLES TO ONE ANOTHER AT THE LOWER END OF THE MAST FOR CONNECTING THE GRAPPLE MEANS THERETO, AND A PAIR OF LOAD ELEVATING MECHANISMS CARRIED BY SAID TURRET AND CONNECTED TO SAID GRAPPLE MENAS, SAID MECHANISMS BEING LOCATED ONE ON 